The present invention relates to the stereo and audio industries, and more particularly, to the field of audio amplifiers for amplifying audio and related methods.
Over the years, the stereo and audio industries have grown dramatically. As additional capabilities of audio and stereo equipment have advanced, continual cost pressure from consumers and increased worldwide competition have, over the years, forced prices audio and stereo equipment down. The referenced audio and stereo equipment includes, for example, audio amplifiers, power boosters, power supplies, receivers, transmitters, radios, clocks, tuners, speakers, tape players and recorders, compact disc players, and various other equipment known to those skilled in the art.
In the power audio amplifier field, many advancements have focused on improved techniques for generation of high acoustic power signals with high bandwidth and low distortion. Also, improvements have been made in methods for supplying power to audio amplifiers. Power audio amplifiers traditionally use two separate power sources, a high voltage source and a low voltage source. A switching transistor is often used to switch between the low and the high voltage sources. Under most circumstances, an audio signal to be output is detected by power sensing equipment. When the power level of the signal exceeds a pre-selected level, the switching transistor thrown so as to supply power from the high voltage source. When the level of the audio signal is below the pre-selected level, the switching transistor is thrown so as to supply power from the low voltage source. However, high levels of power, especially for relatively prolonged periods of time, or as a result of sudden surges, can overheat, and severely damage, the switching transistors and other electronic components of audio amplifiers.
To address the overheating problems, power amplifiers have been developed with temperature controls which attempt to protect the transistors and other electronic components from overheating. Examples of such power amplifiers can be seen in U.S. Pat. No. 5,818,301 to Higashiyama et al. and U.S. Pat. No. 5,331,291 to D""Agostino et al. Although these inventions describe methods to protect components from overheating during relatively prolonged exposure to high voltages, they do not do a good job of protecting components from momentary high voltage surges, such as those occurring during start-up, which can quickly damage the transistors and other electronic components.
To address the power surge problems, circuits have been developed which detect abnormally high voltage levels and cut off, or isolate, portions of a power amplifier circuit in order to protect them. An example of such a circuit can be seen in U.S. Pat. No. 5,847,610 to Fujita. However, such power circuits are poor at addressing power surges during start-up problems, are subject to problems in discriminating between true power surge conditions and false readings. These circuits also little to address thermal overheat conditions, and do not adjust well to different power conditions.
In addition, audio amplifiers have been developed to network, or interface, with automation and networked intercommunication systems within homes, offices, and other settings. These network-enabled amplifiers, however, generally lack the ability to control network functions within the networked system they are integrated into. In other words, the subject network often has a controller to control functions in the audio amplifier, but the audio amplifier is not designed to take advantage, and cannot make use, of network functions to improve its audio performance.
With the foregoing in mind, the present invention advantageously provides and audio amplifier controller for and audio amplifier and associated methods which limits in-rush current during start up and slowly ramps up to a high power and amplifier state. The present invention also advantageously provides an audio amplifier controller which in combination allows for power discrimination capabilities, thermal monitoring capabilities to enhance protection for power audio amplifiers during various power surge and temperature increasing conditions, and network detecting and processing for enhancing interface with, responsiveness to, and control of conditions or activities within a network such as home, office, or other facility automation. The present invention additionally advantageously provides and audio amplifier controller which monitors the current output of the amplifier to protect speakers or other devices by disconnecting the load to the output circuits during high or over current conditions and then continues to monitor the current output to resume normal conditions if desirable. The present invention also provides a controller for and audio amplifier which protects the amplifier from going into and remaining in a circuit protection mode by continuously monitoring for normal current conditions. The present invention further advantageously provides and audio amplifier having and audio controller and associated methods which detects voltage level changes by frequency changes and voltage nulls. The present invention still further provides an audio amplifier with internal network temperature conditions, current conditions, and voltage conditions.
More particularly, the present invention provides an audio amplifier power and temperature controller comprising power receiving means for receiving power from a power source to an audio amplifier; power condition switching control means responsive to the power receiving means for switching components of an audio amplifier during a plurality of power conditions, the power condition switching control means including thermal status monitoring and controlling means for monitoring thermal status of operating values of audio amplifier components and responsively decreasing power to the audio amplifier components to protect the audio amplifier components against damage caused by excess heat and for responsively increasing power when the audio amplifier components return to normal thermal operating conditions; and network condition monitoring means for monitoring network conditions of the audio amplifier to protect and enhance performance the audio amplifier within a network.